1. Field of the Invention
The present invention relates to an etching endpoint determination method, or more particularly, to an etching endpoint determination method making it possible to highly precisely determine an endpoint of etching processing to be performed by utilizing plasma discharge.
2. Description of the Related Art
In dry etching processing of a semiconductor wafer, the luminous intensity of light of a specific wavelength under plasma light emission changes along with the progress of etching of a specific film. The change in the luminous intensity of the light of the specific wavelength under plasma light emission is detected during the etching processing of the semiconductor wafer. Based on the result of the detection, an etching endpoint for the specific film can be detected.
For example, Japanese Patent Application Laid-Open Publication No. 2004-79727 reads that: a plasma-emitted light signal to be generated in an etching apparatus during etching of a material to be etched is acquired; and a linear model or a nonlinear model expressed by a polynomial expression is obtained for the acquired signal. Thereafter, an error of the signal from a calculated value represented by the obtained model is worked out. When the temporal change rate of the error exceeds a predetermined threshold value, the time point is detected as an endpoint of etching.